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Flashcards in DF.5 Deck (13)
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1
Q

What is energy density the measure of?

A

The amount of energy you get per kilogram or litre of fuel.

2
Q

What is cracking?

A

A reaction where a large molecule is made into smaller molecules.

3
Q

What is catalytic cracking?

A

Cracking in the presence of a catalyst.

4
Q

What is a catalyst?

A

A substance that speeds up the reaction by providing an alternative reaction pathway with a lower activation enthalpy and is able to remain chemically unchanged at the end of the reaction.

5
Q

What is the process of speeding up a chemical reaction using a catalyst called?

A

Catalysis.

6
Q

Do the amount of catalyst used in the reaction have an impact on the amount of product formed at the end?

A

No, catalysts do not have an effect on yield, only the rate at which products are formed.

7
Q

What are the two types of catalysis?

A
  • Homogenous catalysis

- Heterogenous catalysis

8
Q

When is the reaction said to involve homogenous catalysis?

A

When the reactants and the catalyst are in the same physical state.

9
Q

When is the reaction said to involve heterogenous catalysis?

A

When the reactants and the catalyst are in different physical states.

10
Q

Describe the four stages of heterogenous catalysis.

A
  1. Reactants form bonds with the surface of the catalyst, this is known as adsorption.
  2. As a result of bonds with the catalyst, bonds in reactants are weaken and eventually broken.
  3. New bonds form between reactants to form product.
  4. As a result of product bonds, bonds with catalyst surface weaken and break, releasing the product molecules, this is known as de-adsorption.
11
Q

What are two key products of cracking?

A

Shorter alkanes and alkene.

12
Q

Larger surface area of catalyst will have what effect on the reaction rate?

A

Increase reaction rate as there is larger surface area for contact with reactants.

13
Q

What is a catalyst poison?

A

A substance that prevents the normal functioning of a catalyst, by adsorbing strongly to the catalyst surface and blocking it, causing it to be inactive.